AR-15 rifles and similarly styled firearms have become a best-selling category of sporting firearms. The main mechanism of operation for the rifle utilizes a gas tube which can be seen by prior art patent by Eugene Stoner U.S. Pat. No. 2,951,424. Which is referred to as the Stoner gas system hereinafter. The Stoner gas system routes gas from a port in the barrel directly to a chamber formed in the bolt carrier. The bolt acts as the piston and is sealed with gas rings.
As the bullet is accelerating rapidly down the bore, it passes the gas port and gas begins to flow into the gas block where it is directed toward the bolt carrier via the gas tube. The pressure is high in the barrel, usually 15,000 psi depending on barrel length until the bullet leaves the muzzle. Typically a firearm gas block is a solid piece of metal that goes over the gas port of a barrel to capture the propellant gas to direct that gas to a gas tube or piston. A problem can occur when the gas pressure is too high or too low.
The AR15/M16/AR10 is a gas operated firearm which uses some of the propellant gases in its normal operation and that gas is expelled through a gas port in the barrel and either goes through a gas tube which ultimately dumps the gas in a chamber known as the bolt carrier which is the Stoner gas system; or is used to propel a piston which pushes an op-rod that impacts the bolt carrier known as ‘piston’ operated firearm.
In either case, when a sound suppressor is used, it creates a great amount of backpressure which has the following adverse affects.
1. Increased fouling which in turn decreases the reliability
2. Increased cyclic rate of fire
3. With the increased rate of fire, it makes it difficult for operators to control the firearm since it is different from what they are used to.
4. Increased cyclic rate also increases parts wear
5. The backpressure leaks gas through the back of the receiver which ends up in the operator's eyes making it more difficult to focus on the target
To solve the problems with the prior art, the Govnah gas regulation system addresses the adverse effects. The Govnah regulated gas block is initially comprised of three different variants. The first variant (v1) uses a sliding block that is configurable to allow the operator to choose from two different positions. One position for a suppressor attached to the barrel and the other position when a suppressor is not used. The second variant (v2) also uses a sliding block but has a third, middle position to completely disable the gas system which then requires the user to manually cycle the action. The ‘no gas port’ position can be used to eliminate any fouling from entering the firearm via the gas tube when a 22LR conversion kit is used. The third position can also have a larger than normal port size to allow more gas into the system for adverse conditions. The third variant (v3) uses a circular block for multiple positions of varying port dimensions, including no port, to allow the user to regulate the amount of gas entering the system to compensate for any changing variables that affect the cycling of the gas operated host firearm.
Known prior art patents include U.S. Pat. No. 7,856,917 issued to Noveske and U.S. Pat. No. 7,921,760 issued to Tankersley. Noveske discloses an adjustable gas block designed to interface with an autoloading firearms gas system and has three positions of adjustment that are selected if a silencer is in use, not in use, or if the user desires to stop the autoloading function of the firearm entirely. This design works by restricting the flow of gas from the gas port in the barrel and does not vent excess gas into the atmosphere around the gas block.
The above device uses a rotating drum with two openings in the drum and a gas port to control the amount of gas that enters into the gas tube which are all pre-determined by the factory. The Govnah uses a sliding or rotating block which can be swapped out by the end user to meet the user's requirements. While the Govnah uses standard military specification gas tubes, the Noveske device uses a proprietary straight gas tube and as a result is elevated higher. In result, the Noveske device will not fit under a rail system. While the Noveske device can by adjusted by hand, this is not ideal when it is hot. It requires a special tool or gloves to adjust safely when hot. The Govnah can be adjusted by any device that can push the adjustment plate, ideally a bullet.
There are applications and benefits for each of the two devices which include providing users with two (v1), three (v2) or multiple (v3) positions for gas regulation on the AR15/M16/AR10 platform using unmodified standard gas tubes; they do not require special tools to adjust the position; they reduce logistic issues in regards to parts availability since they work with standard gas tubes; and they work with drop in ‘piston’ operated conversion kits that are on the market such as the Ares Defense GXR-35 and Osprey Defense OPS-416. Neither of which have a built in mechanisms to manually select the gas intake of the respective systems.
The Govnah regulated gas block (v1 and v2) is low profile which allows it to fit under a rail system and still be accessible for adjustment using the tip of a bullet or other small diameter object to select the gas setting. Since the Govnah regulated gas block fits under a rail system, the design itself is protected by the rail system to prevent any damage or inadvertent changing of the gas setting. The Govnah also uses a symmetrical moving block which controls the gas. Since it is symmetrical, it can be installed two different ways. This allows the user to decide which direction they prefer to have the adjustment plate set.
The Govnah (v3) provides users with a regulated gas block that can quickly adjust to multiple known port diameters to change the amount of gas that is entering the host firearm's gas system without disassembly or special tools. This feature is useful when the user changes any variable that affects the functioning of the gas operated host firearm such as different buffers, sound suppressors, ammunition or springs.
The Govnah also incorporates an alignment hole for installation into the gas block body itself while prior art U.S. Pat. No. 7,921,760 accomplishes this with a separate installation device which requires dimpling the barrel to maintain alignment once the actual gas block is installed. The Govnah doesn't require dimpling since alignment is performed with the actual gas block body not a separate installation device.
What is needed to solve the problem with the prior art gas block is an adjustable gas port assembly that functions as a gas regulator for AR-15 rifles and similarly styled firearms. The present invention uses an adjustable gas block with variable gas port dimensions to control the amount of gas in the gas block before the gas enters into the gas tube or piston.